1. Field of the Invention
The present invention relates to a zoom lens and an imaging apparatus. More specifically, the invention relates to the technical field of compact and high performance zoom lenses which can be advantageously used in imaging optical systems of digital input/output apparatus such as digital still cameras and digital video cameras and the technical field of imaging apparatus utilizing such zoom lenses.
2. Description of the Related Art
Recently, the market of imaging apparatus such as digital cameras has become very large, and users' requirements on imaging apparatus are becoming more diverse. In addition to demand for higher image quality, smaller sizes, and smaller thicknesses, demand for imaging lenses having greater zoom ratios and greater angles of view is becoming very strong recently.
There is great demand for greater angles of view and compactness, and it is particularly desirable to provide a compact zoom lens having a great zoom ratio and a great angle of view exceeding 40 deg in terms of half-angle of view.
For example, there are various types of zoom lenses to be used in digital still cameras, and the lens types listed below can be provided with a small size and a great angle of view.
Known lens types as described above include three-group zoom lenses formed by a first lens group having negative refracting power, a second lens group having positive refracting power, and a third lens group having positive refracting power, which are disposed in the order listed from an object side to an image side (for example, see JP-A-2004-13169 (Patent Document 1), JP-A-2006-113554 (Patent Document 2), JP-A-2007-212636 (Patent Document 3) and JP-A-2007-140359 (Patent Document 4)).
Referring to zoom lenses disclosed in Patent Documents 1 and 2, a first lens group is formed by three lenses to provide a great angle of view.
Zoom lenses disclosed in Patent Documents 3 and 4 are provided with a small size by forming a first lens group using two lenses, In particular, the zoom lens disclosed in Patent Document 4 is provided with a small size by forming a first lens group using two lenses and generating distortional aberrations in an active manner.